Switching circuit and dc-to-dc converter

Abstract

According to one embodiment, a switching circuit includes a high-side switch, a rectifier, and a driver. The high-side switch is connected between a high potential terminal and an output terminal. The rectifier is connected between the output terminal and a low potential terminal, and forward direction of the rectifier is the direction from the low potential terminal to the output terminal. The driver supplies a first voltage to a control terminal of the high-side switch in accordance with a high-side control signal and turns the high-side switch on. The driver supplies a second voltage being higher than the first voltage to the control terminal of the high-side switch when the voltage of the output terminal increases to not less than a predetermined value.

1 . A switching circuit comprising:
 a high-side switch connected between a high potential terminal and an output terminal;   a rectifier connected between the output terminal and a low potential terminal, forward direction of the rectifier being the direction from the low potential terminal to the output terminal; and   a driver supplying a first voltage to a control terminal of the high-side switch in accordance with a high-side control signal and turning the high-side switch on, the driver supplying a second voltage being higher than the first voltage to the control terminal of the high-side switch when the voltage of the output terminal increases to not less than a predetermined value.   
     
     
         2 . The circuit according to  claim 1 , wherein
 the driver includes:
 a detector comparing the voltage of the output terminal and a reference voltage; and 
 a high-side controller outputting the first voltage in accordance with the high-side control signal and outputting the second voltage in accordance with the output of the detector. 
   
     
     
         3 . The circuit according to  claim 2 , wherein the high-side controller operates under a voltage not greater than a power supply voltage supplied between the high potential terminal and the low potential terminal. 
     
     
         4 . The circuit according to  claim 1 , further comprising a low-side switch,
 the rectifier being a parasitic diode of the low-side switch connected between the output terminal and the low potential terminal.   
     
     
         5 . The circuit according to  claim 4 , wherein the driver further includes a low-side controller turning the low-side switch on or off in accordance with a low-side control signal. 
     
     
         6 . The circuit according to  claim 5 , wherein the low-side controller operates under a voltage not greater than a power supply voltage supplied between the high potential terminal and the low potential terminal. 
     
     
         7 . The switching circuit according to  claim 1 , wherein the rectifier is a diode, an anode of the diode is connected to the low potential terminal and a cathode of the diode is connected to the output terminal. 
     
     
         8 . A DC-to-DC converter comprising:
 a switching circuit including:
 a high-side switch connected between a high potential terminal and an output terminal; 
 a rectifier connected between the output terminal and a low potential terminal, forward direction of the rectifier being the direction from the low potential terminal to the output terminal; and 
 a driver supplying a first voltage to a control terminal of the high-side switch in accordance with a high-side control signal and turning the high-side switch on, the driver supplying a second voltage being higher than the first voltage to the control terminal of the high-side switch when the voltage of the output terminal increases to not less than a predetermined value and 
   a controller generating the high-side control signal of a PWM signal in accordance with an input voltage.   
     
     
         9 . The converter according to  claim 8 , wherein
 the driver includes:
 a detector comparing the voltage of the output terminal and a reference voltage; and 
 a high-side controller outputting the first voltage in accordance with the high-side control signal, and outputting the second voltage in accordance with the output of the detector. 
   
     
     
         10 . The converter according to  claim 8 , further comprising a low-side switch,
 the rectifier being a parasitic diode of the low-side switch connected between the output terminal and the low potential terminal.   
     
     
         11 . The converter according to  claim 10 , wherein the driver further includes a low-side controller turning the low-side switch on or off in accordance with a low-side control signal. 
     
     
         12 . The converter circuit according to  claim 8 , wherein the rectifier is a diode, an anode of the diode is connected to the low potential terminal and a cathode of the diode is connected to the output terminal. 
     
     
         13 . The converter according to  claim 8 , further comprising:
 an inductor, a first end of the inductor connected to the output terminal;   a smoothing capacitor connected between a second end of the inductor and the low potential terminal; and   a feedback resistor connected between the second end of the inductor and the low potential terminal, the feedback resistor feeding a voltage back to the controller.   
     
     
         14 . The converter according to  claim 13 , wherein
 the driver includes:
 a detector comparing the voltage of the output terminal and a reference voltage; and 
 a high-side controller outputting the first voltage in accordance with the high-side control signal, and outputting the second voltage in accordance with the output of the detector. 
   
     
     
         15 . The converter according to  claim 13 , further comprising a low-side switch,
 the rectifier being a parasitic diode of the low-side switch connected between the output terminal and the low potential terminal.   
     
     
         16 . The converter according to  claim 15 , wherein the driver further includes a low-side controller turning the low-side switch on or off in accordance with a low-side control signal. 
     
     
         17 . The converter circuit according to  claim 13 , wherein the rectifier is a diode, an anode of the diode is connected to the low potential terminal and a cathode of the diode is connected to the output terminal.